This invention relates to synergistic microbicidal combinations and, in particular, to synergistic microbicidal combinations of 2-methyl-3-isothiazolone with one or more selected commercial microbicides, where the resulting composition is substantially free of halogenated 3-isothiazolone.
Kathon™ CG biocide (3/1 ratio of 5-chloro-2-methyl-3-isothiazolone to 2-methyl-3-isothiazolone) and Neolone™ 950 bactericide (2-methyl-3-isothiazolone) are highly effective preservatives and may be used in combination with a variety of commercially available preservatives to prevent microbial contamination in personal care applications, such as cosmetics and toiletries (see “Kathon™ CG Cosmetic and Toiletry Preservative” Bulletin CS-663, September 1997, and “Neolone™ 950 Preservative for Personal Care” Bulletin CS-707, May 2001, Rohm and Haas Company, Philadelphia, Pa.). U.S. Pat. No. 5,591,759 discloses the use of 1,2-dibromo-2,4-dicyanobutane to stabilize isothiazolone mixtures of 5-chloro-2-methyl-3-isothiazolone/2-methyl-3-isothiazolone (9/1 ratio). Patent application WO 01/50855 discloses preservative formulations for extending the lifetime of cut flowers based on preservative formulations containing acrylic copolymer additives, saccharide derivatives and antimicrobial mixtures, including those based on 2-methyl-3-isothiazolone in the presence of citric acid/citrates.
Many other microbicidal agents are known. These are commercially available for the control of microorganisms in a variety of loci. Sometimes, many microbicides cannot provide effective antimicrobial control even at high use concentrations due to weak activity against certain microorganisms. Without effective microorganism control, loss of product, inferior product, production time loss, health hazard and other problems may occur in the locus treated. There is a need for a method to control various microorganisms that does not rely on high use levels of combinations of different microbicidal agents, but still provides effective overall control of the microorganisms that is both quick and long lasting.
The problem addressed by the present invention is to overcome deficiencies of previous microbicide combinations by providing a combination of microbicidal agents that is more effective than the individual microbicides used alone and that can be used at lower overall levels while providing efficacy similar to the original individual microbicide levels.